1. Technical Field
This document relates to mechanical seals that include one or more rolling diaphragms. For example, this document relates to double rolling diaphragm seals that can be used in conjunction with various types of equipment, including accelerated life testing equipment.
2. Background Information
A rolling diaphragm can be used as a seal between a linear motion component (e.g., piston, actuator shaft, etc.) and a surrounding stationary member (e.g., a cylinder wall, an actuator housing, etc.). Such seals isolate one space from another. Therefore, rolling diaphragms prevent passage of materials, so that environmental contaminants are prevented from entering a linear actuator housing, for example. Rolling diaphragms can also be used to create a pressure vessel with a variable volume.
Rolling diaphragms move with almost no friction because the seal between the linear motion component and the surrounding stationary member is maintained by a rolling action rather than a sliding one. In some cases, the rolling diaphragm seals are made of fabric-reinforced molded elastomer, making them tough and versatile. Rolling diaphragms also are less prone to leaking and hysteresis than other sealing methods, such as O-rings. Generally, rolling diaphragms need little maintenance and/or lubrication.
Accelerated life testing (also known as accelerated wear testing or durability testing) is the process of testing an item by subjecting it to conditions (e.g., cycle time, stress, strain, temperatures, voltage, vibration, pressure, etc.) in excess of its normal service parameters in an effort to uncover faults and potential modes of failure in a short amount of time. Accelerated life testing can be been used to study materials, design concepts, design modifications, and durability variations caused by changes in manufacturing techniques.